A portable Internet system establishes a control connection and a transport connection so as to perform a communication between a mobile terminal and a base station. The control connection means a control channel for transmitting a control message so as to control a communication between the mobile terminal and the base station, and the transport channel means a connection for transmitting other user data excluding the control message transmitted through the control connection. The control message is defined for example in IEEE 802.16 standard.
Connections in the portable Internet system are identified by a connection identifier (CID). A broadcasting identifier is allocated in the control connection so that the control message to be transmitted to all mobile terminals in the cell is transmitted through the control connection appointed by the broadcasting identifier. Meanwhile, a unicast connection identifier is allocated in the transport connection so that all the user data are transmitted in a unicast manner.
Internet protocol version 6 (IPv6) or mobile internet protocol (MIP) is configured to transmit internet subnet information to the mobile terminal using a broadcast protocol message before an internet protocol address (IP address) is allocated to the mobile terminal. The internet subnet information relates to the internet subnet in which the mobile terminal is included. However, since the conventional portable Internet system, for example, IEEE 802.16 Wireless Metropolitan Area Network (MAN)-based portable Internet system, is configured such that a transmission of an upper layer protocol message, such as the IPv6 or the MIP, is performed through the transport connection, the portable Internet system may not broadcast the upper layer protocol message.
Accordingly, in the portable Internet system, the broadcasting can be performed between the base station and the backbone network, but the protocol message is transmitted in the unicast manner between the mobile terminal and the base station. As described above, the protocol message which can be transmitted at one time must be transmitted in the unicast manner to each of the mobile terminals included in the cell, and accordingly, there is a drawback that wireless transmission efficiency is deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.